The present invention relates generally to the field of equipment enclosures and more particularly, to an apparatus for mounting such equipment enclosures and for protecting cables which are connected to equipment housed therein. By way of example, the invention may be applied to the mounting of telecommunications equipment having fiber optic cables connected thereto.
Electronic equipment conventionally comprises an enclosure such as a box-shaped housing containing electronic circuitry. In some instances, the front of such a housing is open so as to provide access to shelves, each of which may be configured with receiving stations for holding electronic circuitry units in a side-by-side relationship. Housings of this nature are prevalent in telecommunications equipment applications. When installed into such housings, one or more of these electronic circuitry units may be connected to a communications network using fiber optic cable. The fiber optic cable carries communication signals to and from the electronic equipment. Typically, each front vertical edge of the housing has a mounting flange that is generally perpendicular to the sides of the housing. The mounting flanges may be used to attach the equipment to a support structure therefor, such as vertical rack, as is well-known to those versed in this art. The rack has two parallel, vertical members which are spaced apart by a distance slightly greater than the width of the housing and each vertical member is typically secured to the floor. The vertical members each provide a mounting surface to which the mounting flanges of the equipment housing may be removably attached. In compliance with the Electronic Industries Association (xe2x80x9cEIAxe2x80x9d) standards, set out in EIA document ANSI/EIA-310-D1992, rack members are typically spaced to correspond to standard housing widths. Standard widths used for housing are typically 19 inches, 23 inches, and 30 inches. (These standards are similar to those of the European Telecommunications Standards Institute (xe2x80x9cETSIxe2x80x9d), as disclosed in ETSI document ETS 300 119-2.) Several racks may be lined up side by side and organized into parallel rows known in this art as equipment line-ups. Each row is separated from the other by a predetermined distance which provides access to the front and back of the electronic equipment so that the equipment may be serviced.
Alternatively, the mounting flanges may be secured to an adapter which is attached in turn to the vertical rack. The latter mounting arrangement is known to those skilled in the art as mid-mounting, and the adapter in question is termed a mid-mount adapter. Generally, the mid-mount adapter provides a web which is generally oriented perpendicular to the mounting flanges of the equipment housing. The mid-mount adapter thereby allows for the equipment in question to be mounted to the rack such that the front face or front surfaces of the equipment housing are spaced apart from the front surface of the rack. Thus, the vertically disposed mounting flanges of the equipment housing will be horizontally offset from the corresponding mounting surfaces therefor which are found on the rack.
Mid-mount adapters are employed for the rack mounting of electronic equipment in order to conform with ETA standards. Newton Instrument Company of Butner, N.C. manufactures a typical standards-compliant adapter (Newton part numbers 21386401 to 21386408) for mounting the housing to the rack. The Newton adapter comprises a planar metal web that is five inches wide, with parallel, symmetrical flanges traversing the longitudinal edges of the web. The cross-section of the adapter is generally U-shaped with the flanges being perpendicular to the plane of the web. The flanges are provided with a plurality of screw holes therethrough. The screw holes correspond to screw holes located in the mounting surface of each vertical member of the rack and in the mounting flanges of the equipment housing. Screws are inserted through the holes in the flanges of the adapter into the corresponding screw holes provided in the rack and in the flanges of the housing. The rack is thus located at or about the mid-section of each side of the housing. This mid-mounting arrangement provides service personnel with access to both the front and rear of the housing when the housing is arranged in equipment line-ups. A disadvantage of this arrangement is that the flange along the front vertical edge of the housing or that of the mid-mount adapter itself protrudes and may at times accidentally catch on equipment or clothing of repair personnel. It has also been known for repair personnel to collide with these protruding edges of the housing or adapter in certain prior art mid-mount adapters.
In a typical installation, the fiber optic cable protrudes from the front of the housing at or near its point of connection with the electronic circuitry unit. The protruding cable hangs vertically over a portion of the front surface of the housing. In a lower portion of the housing, the cable is partially wrapped around a protrusion in the front surface of the housing, as is known to those in this art. The protrusion has a curved surface which the cable follows, causing the cable to be drawn horizontally across the front surface of the housing. At the point at which the cable reaches a vertical edge of the housing, the cable is partially wrapped around the mounting flange and is run either up the side of the housing into a ceiling or down the side of the housing into a sub-floor cable raceway system.
When certain of the known mid-mount adapters are deployed in the foregoing installations, the cables will typically be exposed to potential damage or mechanical disruption at the sides and front of the equipment housing. Moreover, these unprotected cables may hang loosely from the front of the housing. In this arrangement the cable is often caught on the clothing and equipment of maintenance personnel when they service the electronic equipment contained within the housing. When the cable catches, it may also disconnect, which may lead to increased maintenance costs. If slack in the cable is reduced, problems may also arise because the cable must then be wrapped tightly around the mounting flange of the equipment housing or adapter flange. This causes the cable to bend unduly, often forming a bend radius of less than one inch. If the fiber optic cable is bent with a radius of less than one inch then a Bellcore industry standard for bend radius pertaining to fiber optic cable is not satisfied. This standard, set out in Bellcore Generic Requirements document GR-78-Core, at paragraph R5-34[170], states that xe2x80x9c[s]ingle optical fiber cables shall not be bent to a radius of less than one inch at any stage during manufacturing or field deployment.xe2x80x9d A bend radius of less than one inch in the cable may cause fiber fracture which causes a loss of the signal being carried by the cable. If fiber fracture occurs, the cable must be replaced. Users of the communication signal carried by the damaged cable also may lose revenue for the time that they are unable to use the fiber optic cable.
In other known installations, the cable is guided alongside the equipment housing by an extruded plastic three-sided conduit, or cable management system, with a rectangular cross-section. The conduit""s opposing sides are formed by a plurality of narrow resilient fingers. The remaining side is comprised of a continuous web. The resilient fingers protrude in the same direction from the longitudinal edges of the web and are perpendicular to the web. The conduit is vertically attached to the rack and the cable is wrapped between two or more narrow fingers to hold it in place as it traverses the conduit into either the ceiling or sub-floor, as previously described. The cable system may alternatively be configured to have a second three-sided conduit. In this alternative configuration, a second set of resilient fingers protrude perpendicularly from the longitudinal edges of the web but in the opposite direction of the first resilient fingers. This two channel arrangement has an H-shaped cross-section. An example of this cable management system is the Fiber-Duct(trademark) FMPVS manufactured by Panduit Corporation of Tindley Park, Ill. A conventional conduit typically only serves the function of routing cable; it can not generally be used to mount electronic equipment to a rack.
While the cable management systems of the type described above may secure or protect cables from damage or disruption when same are running alongside the equipment housing, in certain of such cable management systems the cables in question may nevertheless still exhibit the tendency to hang loosely from the front of the equipment housing. Thus, the very same problems associated with loose cables might be encountered with the foregoing cable management systems when compared to installations deploying known mid-mount adapters. Likewise, if it is sought to reduce cable slack at the front of the equipment housing, certain of the said cable management systems may produce an undesirable bend radius due to the cable being wrapped tightly around the mounting flange of the equipment housing or around the mid-mount adapter flange. This problem was previously explained in relation to known mid-mount adapters.
Based on the foregoing, it would be desirable to develop alternative means for mid-mounting electronic equipment and for routing cable connections thereto while attempting to alleviate or minimize excessive bending or other mechanical disruption of the cables.
The invention consists of an apparatus for mounting an equipment enclosure to a support structure. The support structure has a first and a second mounting surface, which are generally coplanar and spaced apart to accommodate positioning of at least a portion of the equipment enclosure therebetween. The equipment enclosure is for housing equipment which is connectable to at least one signal carrying cable. According to one broad aspect of the invention, the apparatus comprises:
a) a first abutting member for attachment of said apparatus to one of said first and second mounting surfaces of the support structure;
b) a second abutting member spaced apart from said first abutting member and providing a third mounting surface for attachment to said equipment;
c) at least one bridging member connecting said first abutting member to said second abutting member;
d) at least one cable retaining member, each cable retaining member depending from one of said first abutting member and said second abutting member, to thereby form a cable cavity which is generally defined by said first abutting member, by said second abutting member, by each said bridging member and by each said cable retaining member, an d into which said at least one signal carrying cable is locatable; and
wherein the first abutting member, the second abutting member, each bridging member and each cable retaining member are oriented such that an opening is provided between said first and second abutting members through which said at least one signal carrying cable may be introduced therethrough and into said cable cavity in a direction generally transverse to a longitudinal axis of said at least one signal carrying cable.
According to another broad aspect of the invention , there is provided a bend radius control apparatus for the signal carrying cable. The signal carrying cable is connectable to equipment housed in an enclosure therefor. The enclosure has an edge around which the cable is to be redirected as to its orientation. The bend radius control apparatus comprises an elongate member having a generally U-shaped cross-sectional configuration with free terminal ends and an apex portion located therebetween. The apex portion presents a predetermined radius of curvature. The signal carrying cable, when said elongate member is attached adjacent said edge of the enclosure, contacts said elongate member instead of said edge at the apex portion of the member to thereby cause redirection of the orientation of the signal carrying cable while maintaining the signal carrying cable at a bend radius which is no less than said predetermined radius of curvature.
In an illustrative embodiment of the present invention the mounting apparatus may additionally comprise the bend radius control apparatus.
With respect to further illustrative embodiments of the present invention, the bridging member of the mounting apparatus may be a web and the at least one cable retaining member thereof may be a tongue. The web may have a longitudinal first edge and a longitudinal second edge, wherein the first abutting member of the mounting apparatus depends from the web adjacent the longitudinal first edge and the second abutting member of the mounting apparatus depends from the web adjacent the longitudinal second edge. The second abutting member and first abutting member both may depend generally in the same direction away from the web. The tongue may protrude from a free longitudinal edge of the second abutting member, and may extend towards the first abutting member.
With respect to yet further illustrative embodiments of the present invention, the apex portion of the bend radius control apparatus may be parallel to a longitudinal axis of the web of the mounting apparatus. A free terminal end of the elongate member of the bend radius control apparatus may be attached to the web so that the second abutting member is interposed between the free terminal ends of the elongate member to thereby define a surface which overlaps the second abutting member of the mounting apparatus.